Centrifugal casting



- SeptQB, 1946. l H. G. sPEHT 2,406,860 l CENTRIFUGAL CASTING l FiledJune 18,-1943 3 Sheets-Sheet l '24u/5 V` f5' 24 ATTORNEY H. G. sPx-:cH-r2,406,860

CENTRIFUGAL CASTING Sept. 3, 1946.

3 Sheets-Sheet 2 fig-4L" Filedv June is, 1945 INVENTOR HMBQYRY E1. f.

"w//TTORNEY Sept 3, 1946. H. G; sPEcH'r 2,406,850

`CENIRIFUGAL CASTING Filed June 18, 1943 5 Sheets-Sheet 5' ATTORNEYPatented ,Sept 3, 1946 UNITED STATES PATENT OFFICE CENTRIFUGAL CASTINGHarry G. Specht, Montclair, N. J. Application June 18, 1943, Serial No.491,305

11 Claims. 1

The present invention relates to centrifugal casting, and particularlya, casting machine for the production by centrifugal casting of ingots,bars, and specially shaped metal bodies, such as may be used for aparticular purpose, as for instance, for producing gun barrels.Centrifugal casting produces a metal structure having many advantages,such as iine grain, uniformity, denseness, freedom from voids, andpurity. This last advantage is characteristic of centrifugal casting,due to the fact that the pure metal may be directed outwardly in themoulds through centrifugal casting machine wherein the moulds e willeiiectually withstand the expansion and contraction, resulting from theintroduction into the moulds of the hotr molten metal, without permanentdistortion or cracking. Another difficulty has been experienced in thecooling of the moulds to prevent retention of heat transferred to themoulds from the molten metal that would be in excess oi the criticaltemperature of the metal. Attempts to meet this cooling problem haveconsisted in the use of cooling iiuids, air, fins and other such means,but these have been unsuccessful for the most part, due to complicationoi structure and increased tendency of the moulds to distort and crack.

It is an object of the present invention to provide a centrifugal'casting machine wherein the moulds are free to expand from a coldtemperature to a hot temperature, without permanent distortion orcracking, and wherein the moulds will be eiectually cooled during thecentrifugal casting process. It is pointed out by way of example, thatin pouring certain metals above 2000 degrees, it is neccessary to coolthe moulds down to approximately 600 degrees, so that the nettemperature of the moulds after the metal is poured into them will notbe greater than the critical temperature of the metal or approximately1400 degrees.

it is proposed in the present invention to provide a centrifugal castingmachine having sectional moulds, one mould being provided for eachingot, bar, or the like, and wherein expansion and contraction may takeplace within the individual moulds in all directions Without imposingdistortion or cracking forces upon the individual or associated moulds.

It is further proposed to provide an individual mould structure having aWall of substantially uniform thickness, so that there is asubstantially uniform transfer of heat, and furthermore to provide anexposed surface, subject to the cooling effect of air during therotation of the moulds, which is substantially proportiona1 to the mouldcavity surface, the external shape `oi the mould being shaped tecorrespond substantially to the internal cavity shape.

A further Objectis to provide a moulding machine wherein the moulds maybe conveniently assembled or disassembled, either entirely orindividually, the arrangement permitting removal and replacement of anyindividual mould de sired.

Another object is to facilitate the removal of the moulded pieces, thearrangement permitting individual pieces to be removed if desiredwithout removal of the mould from the machine.

Another object is to provide a centrifugal cast ing machine wherein theindividual moulds are such that an adequate chilling ratio may bemaintained between the molten metal to be poured into the moulds and themoulds themselves, it being pointed Iout that from a practicalstandpoint this ratio should be approximately from 3 to 1, 5 to 1.

A further object is to provide a centrifugal casting machine ofrelatively large capacity, wherein the mould units are so arranged withrespect to the axis of rotation that dynamic balance may be maintainedduring the operation of the mould, and whereby relatively high speed maybe attained both from the standpoint of centrifugal force upon the metaland cooling ac tion upon the moulds, it being pointed out thatinpractice the surface speed of the moulds, according to the invention,may be about 4000 R. P. M.

It is a further object to provide a centrifugal casting machine whichwill permit the effective removal of gases that collect during thepouring operation, and to this end it is proposed to provide acentrifugal casting machine wherein the moulds revolve around ahorizontal axis, and wherein the pouring space is disposedlongitudinally of the axis and centrally of the mould units disposedcircumferentially about the axis.

With the above and other objects in View, an embodiment of the inventionis shown in the accompanying drawings, and this embodiment will behereinafter more fully described with reference thereto, and theinvention will be finally pointed out in the claims.

In the drawings- Fig. 1 is a side elevation of a centrifugal castingmachine, according to the exemplary illustrated embodiment of theinvention.

Fig. 2 is an end elevation.

Fig. 3 is a side elevation of the mould mounting cage member, removedfrom the machine.

Fig. Il is an end elevation thereof.

Fig. 5 is a longitudinal vertical sectional View of the cage and mouldassembly, removed from the machine, this view being taken along the line5 5 of Fig. 6.

Fig. 6 is a transverse vertical sectional View, taken along the line B-Eof Fig. 5.

Fig. 7 is a vertical longitudinal sectional View, taken along the line'l--l of Fig. 6.

Fig. 8 is a top plan View of one of the individual moulds.

Fig. 9 is a bottom plan view.

Fig. 10 is a side elevation thereof.

Fig. l1 is a plan view of the two parts of the mould shown in openposition, and with the cast piece in one of the parts.

Fig. 12 is a side elevation of the cast piece removed from the mould.

Fig. 13 is an end view thereof.

Fig. i4.- is a side elevation of the cast piece after removal of thelongitudinal rib containing impurities.

Fig. l5 is an end view thereof.

Fig. 16 is a transverse vertical -sectional view of a mould assemblyaccording to the invention wherein the individual moulds are ofdifferent forms, to produce a variety of cross sectional shapes.

Similar reference characters indicate corresponding parts throughout theseveral figures of the drawings.

Referring to the drawings the centrifugal casting machine, according tothe illustrated exemplary embodiment of the invention, comprises arotatable mould carrying cage member consisting of a plurality ofcircumferential track rings le, two such rings being employed in theillustrated embodiment, and to the inner peripheries of which aresecured, by welding or other suitable methods, a series of logitudinallyextending spaced radially disposed bars Il, the inner longitudinalsurfaces I2 of which are slightly tapered from end to end, so that thesesurfaces diverge toward the entrance end of the cage to facilitateinsertion and removal of the moulds, as will presently more fullyappear.

In the operation of the machine the cage is horizontally disposed withina supporting power unit, which rotates the cage and the moulds carriedthereby about a horizontal axis. This unit comprises a pair of bearingframes l3|3, which are of inverted U-form and are each provided upon thehorizontal bases of each of the side legs with bearing standards I4,which constitute bearing supports for drive shafts l5-l5, in addition tothe bearing supports provided for these shafts in the side legs. Uponthe shafts i5, between the side legs and the bearing standards M, thereare provided flanged pulley wheels i6 which engage and support the trackringsI lil of the cage, the axes of the shafts l5 being disposed inplanes radial to the axis of the cage and disposed at angles ofsubstantially 90 to each other. The shafts I5 are driven from a motor l1provided with pulleys I8 and I9 connected 'by belts 2! and -2-i topulleys 22 and -23 provided respectively upon the ends of the shaftsIll-l5.

Idler pulleys 24 engage the track rings IO at their upper sides, thesepulleys being mounted upon shafts 25-25 journaled in slide bearings 26disposed in slideways 2l provided at the upper corners of the framesthese slideways being disposed in planes radial to the axis of the cageand disposed at angles of substantially to each other and to the radialplanes of the shafts |5|5. Support screws 28 carried by the frame engagethe lower ends of the bearing blocks 28 and are normally adjustedinwardly so that the pulleys ride freely upon the tracks lll. Byadjustment of these screwsoutwardly the bearing blocks 26 may be movedoutwardly in the slideways 2, to raise the idler pulleys to disengagethem from the tracks lil, and also to provide suflicient clearance forthe tracks to be disengaged 'from the drive pulleys l by raising thecage vertically, for the purpose of convenient engagement anddisengagement of the cage with respect to the drive unit. The operationmay be conveniently carried out by overhead crane, or by a suitableelevating dolly wheeled beneath the cage.

The mould units are of segmental form and correspond in number to thesupporting bars Il of the cage, one unit being disposed between eachbar, and each bar providing an outwardly disposed support for theadjacent marginal edges of two of the adjacent mould units. Each mouldunit comprises a pair of complementary mould parts 29 having alongitudinally extending mould cavity et shaped to form half of themoulded piece. In the illustrated embodiment the moulded piece is shownby way of example as a circular cross-section tapered bar, such as mightbe used in forming a gun barrel. In this case the cavities 3i] aretapered and this taper preferably corresponds to the taper of thesurfaces l2 of the bars Il. The outer wall surface of the mould isconcentric to the mould cavities and terminates at each side in alongitudinally extending shoulder ledge 3| adapted to seat upon theinner surface l2 of the bar Il of the cage, the side curfaces of themould unit being disposed in radial planes intersecting the centralplanes of the bars Il which support it at each side. The cross sectionalshape of the separate mould units is of substantially key-stone form, sothat when the several units are assembled in concentric relation withinthe cage each unit is supported by the adjacent units. Their innerperipheral surfaces are concavely curved, so that the inner periphery ofthe assembled units is cylindrical and concentric to the axis of thecage. Extending longitudinally of the inner periphery of each mould unitis a slot 32 formed by complementary recesses in the inner side surfacesof each of the mould parts, spacer lugs 33 being provided at each end ofthe slot to maintain the spaced relation of its side walls and so thatthe two parts of the mould will not collapse toward each other. In eachof the side surfaces ci the moulds there are provided longitudinallyextending grooves 3l for receiving tie rods for maintaining theassembled relation of the moulds within the cage, as will presently morefully appear.

The moulds are slightly longer than the bars Il of the cage, so thatthey project at each end for the purpose of mounting thereon the closureend plates 35--35, these end plates being in the form of centrallyapertured rings having outer and inner peripheral flanges 36 and 31between which the ends of the mould units are positioned.

The two end plates are tied together by a series of tie rods 38,disposed in the grooves 34 of the mould units, and engaged at theirthreaded ends through suitable holes in the end plates where they aresecured by nuts 39, relation of the mould units and end plates the outerperipheral flanges 3E of the end plates are in opposed relation to theends of the bars Il, so as to position the assembled mould units againstrelative longitudinal movement, this opposed relation beingsuch howeverthat the end plates may be tightly secured upon the ends of the mouldunits without interference'from the bars ll.

The bars I l support the assembled mould units along the shoulder ledges3l against the outward centrifugal force of the rotating cage, but thearrangement provides for complete expansion and contraction movement ofthe mould units radially, circumferentially and longitudinally. VIt willbe noted that the open form of the cage and the marginal edge support ofthe units therein allows unrestricted expansion and contractionradially, the slotted form of the units permits circumferentialexpansion and contraction to take place entirely within each unit, andthe disposition vof the closure end plates beyond the ends of the cagepermits free longitudinal expansion and contraction. The disposition of`the tie rods within the recesses 34 in the side Walls of the mouldunits is also a factor in the complete freedom of expansion andcontraction movement, as heat transfer to these tie rods will besufficient to cause them to expand and contract in substantialconformation with the expansion and contraction of the mould unitsthemselves. l

In operation, the assembled mould units in the rotatable cage aremounted in the power unit, as shown in Figs. 1 and 2, and rotation isimparted thereto at the desired speed to create necessary centrifugalforce. The molten metal is introduced into the mould through the centralpassage therethrough by any suitable feed means, the centrifugal forcecausing the metal to move outwardly in the moulds and to build uptherein under centrifugal force untilthe moulds are completely charged,this point being predetermined, so that the mould cavities arecompletely nlled and the metal extends partially inwardly in theentrance slots.

Due to the horizontalH` arrangement ofthe mould with its longitudinallyextending mould cavities, slots, and central passage glass that form mayreadily escape without being trapped. The complete symmetry 'of themould, and the equal support afforded by the drive pulleys, establishesdynamic balance so that relatively high rotational speed may beattained, without creating excess strain upon any of the parts.

The cross sectional shape of the individual mould units, and the mannerin which they are supported in the cage along the longitudinal bars Ilpermits free expansion and contraction during the heating and coolingstages, the outwardly divergent side walls of the mould units supportingthe individual units against the next adjacent units, and thelongitudinally extending entrance slots, permitting the strain of thecircumferential expansion movement to be taken up entirely within-theindividual mould unit without any tendency to distort or crack withinitself or to exert distorting or cracking force upon the adjacent mouldunits. The substantially uniform thickness of the outer walls of themould units, and their relatively large ex- In the assembled` posedsurface conforming to the cross sectional shape of the mould cavity,assures effective and uniform cooling, so that the mould walls Will notretain heat in excess of the critical temperature of the metal. v

The dross or impure metal Will be segregated in the flange formationdisposed in the entrance slot, and as shown in Figs. 12 to 15 thisflange Mi may be readily removed from the centrifugally cast body All,so that the latter is in the form of a predetermined cross-sectional barentirely free rom impurities, and with a minimum waste of metal from theremoval of the impure metal. Upon cooling the cast bars may be readilyremoved, either by removing the individual moulds from the cage, or bydriving the bars from the moulds while the latter remain in the cage,the end plates being removed for this purpose and a suitable forcingtool being applied to the small ends of the bars to force themlongitudinally from the divergent ends of the tapered mould cavities.

In Fig. 16 there is illustrated a mould assembly in which the individualmoulds are of dilerent cross sectional shape to produce a variety ofshapes of bars. These are identified by the letters A to H, the mould Abeing a circular cross-section mould, similar to those illustrated inFigs. l to 15, the mould B being hexagon, mould C Octagon, the mould Dsquare with chamfered corners, the mould E square, the mould F pointedsquare, the mould G half hexagon, and the mould H half round. In thecase of the mould units A, IB, C and D, which have a contracted entranceslot, the mould units are preferably split to facilitate the removal ofthe moulded pieces, while in the case of the mould units E, F, G and H,which each have slightly divergent side walls and an entrance openingformed by the inner ends of these side walls, the mould units arepreferably one-piece form. In each case the cooperative side surfaces ofthe several mould units and their engaging relation with the bars Il areidentical, so that it is possible in one assembly to include any numberof the individual Shapes, or, as in the arrangement illustrated in Figs.l to 15, to provide a complete assembly of any one of the severalshapes.

I have illustrated and described a preferred and satisfactory embodimentof the invention, but it will be understood that changes may be madetherein, within the spirit and scope thereof, as dened in the appendedclaims.

What is claimed is:

1. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcircumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis, there being openspaces between said mould support members extending longitudinally insubstantially parallel alignment with said axis, and a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting members.

2. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcircumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis and disposed inplanes radial to said axis, there being open spaces between said mouldsupport members extending longitudinally in substantially parallelalignment with said axis, and a plurality of longitudinally disposedmould units carried within said carrier in concentric relation about andin parallel alignment with said axis, respectively disposed in saidlongitudinal spaces of said carrier and each supported along itslongitudinal edge portions by said mould supporting members.

3. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcircumferentially spaced mould support members extending longitudinallyin. substantially parallel alignment with said axis and havinglongitudinally tapered mould support inner surfaces, there being openspaces between said mould support members extending longitudinally insubstantially parallel alignment with said axis, and a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach having longitudinally tapered shoulder ledge surfaces along itslongitudinal edge portions engaged with said tapered surfaces of saidmould supporting members.

fl. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including longitudinally spaced trackring members concentric to said axis and a series of olrcumferentiallyspaced mould support members extending longitudinally in substantiallyparallel alignment with said axis and secured to the inner peripheriesof said ring members, there being open spaces between said mould supportmembers extending longitudinally in substantially parallel alignmentwith said axis, and a plurality of longitudinally disposed mould unitscarried within said carrier in concentric relation about and in parallelalignment with said axis, respectively disposed in said longitudinalspaces of said carrier and cach supported along its longitudinal edgeportions by said mould supporting members.

5. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal L axis including longitudinally spacedtrack ring members concentric to said axis and a series ofcircumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis and secured to theinner peripheries of said ring members, there being open spaces betweensaid mould support members extending longitudinally in substantiallyparallel alignment with said axis, a power unit including drive pulleywheels engaging and supporting said track ring members, and a pluralityof longitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting members.

6. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including longitudinally spaced trackring members concentric to said axis and a series of circumferentiallyspaced mould support members extending longitudinally in substantiallyparallel alignment with said axis and secured to the inner peripheriesof said ring members, there being open spaces between said mould supportmembers extending longitudinally in substantially parallel alignmentwith said axis, a power unit including a plurality of pulley wheelsengaged with said track rings at equally spaced points disposed inradial planes of said axis, and a plurality of longitudinally disposedmould units carried within said carrier in concentric relation about andin parallel alignment with said axis, respectively disposed in saidlongitudinal spaces of said carrier and each supported along itslongitudinal edge portions by said mould supporting members.

'7. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series o1circumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis, there being openspaces between said mould support members extending longitudinally insubstantially parallel alignment with said axis, a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting members, each of said mould units having a mould cavityextending longitudinally in substantially parallel alignment with saidaxis enclosed at its outer side, and an entrance slot at its inner sideextending longitudinally in substantially parallel alignment with saidaxis, the outer peripheral wall portions of said mould unitssubstantially conforming to the form of said mould cavities and beingprojected outwardly in said longitudinal spaces.

8. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcireumferentially spaced mould support members extending longitudinallyin substantially parallel alignment With said axis, there being openspaces between said mould support members extending longitudinally insubstantially parallel alignment with said axis, a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting members, each of said mould units having an open-ended mouldcavity extending lon gitudinally in substantially parallel alignmentwith said axis enclosed at its outer side, and an entrance slot at itsinner side extending longitudinally in substantially parallel alignmentwith said axis, and closure end plates secured upon the ends of saidmould units to close the open ends of the mould cavities.

9. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcircumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis, there being openspaces between said mould support members extending longitu dinally insubstantially parallel alignment with said axis, a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting members, each of said mould units having an open-ended mouldcavity extending longitudinally in substantially parallel alignment withsaid axis enclosed at its outer side, and an entrance slot at its innerside extending longitudinally in substantially parallel alignment withsaid axis, and closure end plates secured upon the ends of said mouldunits to close the open ends of the mould cavities, each of said endplates being disposed outwardly of the ends of said mould supportingmembers in longitudinally opposed relation thereto.

10. In a centrifugal casting machine, a mould carrier adapted forrotation about a longitudinal axis including a series ofcircumferentially spaced mould support members extending longitudinallyin substantially parallel alignment with said axis, there being openspaces between said mould support members extending longitudinally insubstantially parallel alignment with said axis, a plurality oflongitudinally disposed mould units carried within said carrier inconcentric relation about and in parallel alignment with said axis,respectively disposed in said longitudinal spaces of said carrier andeach supported along its longitudinal edge portions by said mouldsupporting 'members each of said mould units having an open-ended mouldcavity extending longitudinally in substantially parallel alignment withsaid axis enclosed at its outer side, and an entrance slot at its innerside extending longitudinally in substantially parallel alignment withsaid axis, and closure end plates secured upon the ends of said mouldunits to close the open ends of the mould cavities, and tie rodsextending between said end plates and arranged between the side walls ofsaid mould units.

11. In a centrifugal casting machine, a mould 10 carrier adapted forrotation about a longitudinal axis, anda plurality of longitudinallydisposed mould units carried within said carrier in concentric relationabout and in parallel alignment with said axis, each of said mould unitscomprising a segment of a substantially cylindrical mould assembly, andeach having within it a mould cavity defined by its outer wall and itstwo side walls and extending longitudinally in substantially parallelalignment with said axis, and eachhaving at its inner side in spacedradially opposed relation to said outer wall a centrally disposedentrance slot extending longitudinally in substantially parallelalignment with said axis, the external side surfaces of each of saidmould units being in radial planes of said axis and abutting theexternal side surfaces of the adjacent units at the inner periphery ofsaid cylindrical mould assembly and in circumferential line with saidentrance slots, and the outer wall of each of said units between saidexternal side surfaces being of substantially uniform thicknesses, andsubstantially conforming to the cross-sectional form of its respectivemould cavity, said mould carrier comprising circumferentially spacedmould supporting means having spaces between them wherein said outerwalls of the mould units are exposed to the surrounding air.

HARRY Gr. SPECHT.

